critical

Sensible interpretation of rawCritical:

1. false, meaning non-critical, if:

• absent (rawCritical == null). Valid according to X.509.

• rawCritical == 0x00. Illegal encoding because the value should be absent but happens in practice, and we need to tolareate it.

2. true, meaning critical, if in 0x01..0xFF. Anything but 0xff is illegal but still happens in practice,.